Anthony Edwards photo
Bryan Raiche of Rutland flips off a jump during the opening day of the Mouse Run terain park at Killington Resort on Saturday.

Thanks to ideal temperatures and snowmaking upgrades, nine of the 18 ski resorts in the state have trails open, accounting for nearly 20 percent of the skiable terrain in Vermont.

According to the Vermont Ski Areas Association, that’s the most terrain open at this date since the 2008-09 season.

Parker Riehle, the VSAA president, said Wednesday the strong start to the season can be attributed to the combination of ideal weather conditions and the upgrades made by the state’s resorts in their snowmaking capacity.

Riehle said snowmaking coverage statewide has reached 80 percent of the trails after upgrades during the off season. He said that’s an improvement from four years ago.

“For sure, we’ve increased our snowmaking coverage by at least 10 percentage points since then,” he said. “I know coming into this season from last year the resorts were below 75 percent, but with all the off-season expansions we were able to break the 80 percent statewide mark, which is pretty incredible.”

Jay Peak and Burke Mountain invested a combined $1.5 million in snowmaking upgrades.

“Burke Mountain had its earliest and most successful opening ever, opening Dec. 1,” said Hannah Collins, Burke’s marketing manager. “And with the new upgrades in our snowmaking equipment we were also opening with the most trails that we ever have.”

That ability to make snow is crucial when weather conditions aren’t ideal. So far, this early in the season, snowfall has been in short supply. “We haven’t had a whole lot, nothing major,” Riehle said. “But we have had a fair amount of snowfall in the upper elevations ... that’s just enough to top things off.”

Last year was a disappointing season for the ski industry. The season for many resorts in the state came to an abrupt halt after a summerlike hot spell in March.

The state’s ski areas reported 3,903,171 skier and snowboarder visits during the 2011-12 season — down 10.5 percent from the 4,365,906 visits the previous season, which was the best season since 2004-05.

Riehle said a good start to this season has given resorts a jump on meeting what’s expected to be pent-up demand by skiers and snowboarders.

“In terms of sort of business levels we’ve heard so far, actual skier visits, very positive for those early openings around Thanksgiving and the weekends since,” he said. “Resorts are reporting numbers definitely up, or up above last year’s levels.”

Several of the state’s resorts boasted early openings, including Killington, Okemo Mountain, Jay Peak, Smugglers’ Notch and Burke Mountain.